We've heard about the studiousness and the leadership. We've heard the disarming jokes.

Where does one stop and the other start? For Robert Griffin III, it's a well-defined line.

``Can't be `on' all the time,'' the rookie quarterback said with a smile and a shrug as he strolled through the Washington Redskins locker room Wednesday. ``Guys would get discouraged. You've gotta be fun to be around.''

Athletes are well-known for having on-off switches. Some of the nicest guys around become maniacs when they put on a uniform. Still, knowing when to be goofy and when to be serious isn't as straightforward as it sounds, as anyone in any workplace knows.

Teammates and coaches say Griffin already has it down pat, even though he's just arrived in the NFL.

``Real professionals are able to do that,'' linebacker Lorenzo Alexander said. ``Some players aren't able to separate the two, but he has a great knack, especially for a young guy.''

The Barney dinosaur socks made another appearance in the locker room a week ago. Griffin's weekly session with reporters is always good for at least a couple of good chuckles. Before Sunday's game against the Tampa Bay Buccaneers, he was high-fiving and posing with fans when he emerged from the tunnel - something most players don't do - then flipped on the serious side in a matter of moments to start pregame warmups.

By the end of the game, any doubt that Griffin studies the playbook and takes practice seriously was eradicated when a malfunctioning headset forced him to improvise during the game-winning drive in the final two minutes. Griffin cleverly anticipated a blitz on the second play based on the result of the first play, so he called a quick pass that turned into a 20-yard gain for tight end Fred Davis.

Once the 24-22 win was complete and the Redskins were 2-2, Griffin naturally was in a festive mood with his teammates, but he was the only quarterback to celebrate a victory Sunday by stopping to sit on the stadium tunnel floor and do the now-familiar ``Griffining'' pose with Olympic track and field medalist Kellie Wells.

``Everybody's got a different personality,'' coach Mike Shanahan said. ``Robert, it's very natural for him to be very businesslike. He does have a great sense of humor, where he can change very quickly from being very serious to being in a very jovial, joking mood. But things come pretty easy to him.''

Teammates say it's no doubt a product of Griffin's background. Both parents were in the military, where on-duty and off-duty are clearly delineated.

``He was just brought up in that sense to know that, hey, when it's business, it's business,'' receiver Santana Moss said. ``He's all about business when you're really around him, and then being a young guy, you're going to have to live some time - and you can see that in him. He has fun. You can tell that this is not just something that he dreamed about and now he's here. Nah, he takes this very seriously.''

Notes: Griffin wore pink cleats and a pink left glove at practice as part of the NFL's annual breast cancer awareness campaign. The sleeve he always wears on his left arm was white, but he said a pink sleeve was on the way. ... Sunday's game was the first in which Griffin deliberately put his hands in the air after handing the ball off instead of pretending he still had it, part of a plan to reduce the number of hard hits he takes from defenders. Shanahan also made it to point to discuss the matter with the referee before the game. ``One time I carried out my fake and didn't put my hands up, and he came and found me, and he said: `Make sure you put your hands up,''' Griffin said. ``They protected me a lot more out there as a quarterback, which is how it's supposed to be.'' ... WR Aldrick Robinson, who suffered a concussion in a pregame collision Sunday, will undergo tests Thursday to see if he can resume contact.